A Maryland student gathered explosives materials and a shotgun for an attack she was planning at her school next month, police said Monday.

The Frederick County Sheriff’s Office said the student, 18-year-old Nichole Cevario, was immediately removed from Catoctin High School Thursday and taken to a hospital for help with mental health issues.

After she is released from the hospital, police plan to serve an arrest warrant for alleged possession of explosive and incendiary materials with the intent to create a destructive device. The sheriff’s office said they found a shotgun, ammunition and bomb-making materials that included shrapnel, fuse material and fireworks at her home.

Police said her journal "clearly spelled out" her plan for a shooting, which included a timeline, details about emergency procedures associated with drills conducted by staff and information on the school deputy assigned to the school.

Officials are convinced those plans might have come to fruition if one of her parents hadn't told school officers about them, the Frederick County Sheriff's Office said on Monday.

Michael Doerrer, a spokesman for Frederick County Public Schools, told The Frederick News-Post that staff previously had no indication Cevario was planning any kind of violence. Police said the attack was planned for April 5.

Police said they could not be sure she would have had the "will" to carry out the attack, but they said she planned to die on the date she identified in the journal.

The Associated Press reported that a man who answered the phone at Cevario's home and her attorney, Alan Winik, declined to comment.

No weapons or explosive material ever made it to school grounds, police said.

"The fact that a young woman could have this in her mind, this way of thinking and planning out and carrying out an attack much like Columbine or Sandy Hook," Jenkins said. "It shocks the conscience to see that someone at that age could be thinking like that."